Dear Frank, I am sorry to join this conversation so late but I have been a bit busy since your original posting. I have followed your directions in Google maps with exactly the results you predicted and then I have done the same using Google Earth which has a few additional useful functions.
Firstly, it can display a lat/long grid which instantly identifies the misalignment between the marked lines and lines of longitude. Secondly it has a ruler function which gives the distance and bearing between two marked points and, if you mark the extremities of the marked lines, you discover that they are aligned about 1.5 degrees east of true north. However, the best thing about Google Earth is the time travel function. Go to the menu and select View/Historical Imagery and a slider appears at the top/left of the image which allows the selection of images from 1945 to 2013. If you select 9/1999, then an image appears which shows the entrance to the dome as it was for the millennium celebrations(see attached image). Lo and behold, there is an obelisk sundial at the entrance to the dome. It appears to be sensibly marked out and is properly aligned to true North although the shadow seems well short of the equinoctial line for an image date of 09 September. I wonder if this dial is the one made by David Harber and listed in the BSS Register of 2005 as #5032. Best wishes, Geoff -----Original Message----- From: sundial [mailto:[email protected]] On Behalf Of Frank King Sent: 23 August 2014 16:12 To: [email protected] Subject: Shaggy Longitude Story Dear All, Here is a cautionary tale. In summary: NEVER believe ANYTHING without checking! A little while ago, Doug Bateman mentioned that there were some lines of longitude marked in the paving of Peninsula Square by the O2 Arena in London. You can see these as follows... Enter Google Maps and, into the search box, key in: 51 30 4.75 00 00 15.91 Google allows this syntax for latitude and longitude. You will find yourself on the Greenwich Peninsula just south of the O2 Arena. Now zoom in as far as you can and you will see a white line running roughly north-south flanked by two black lines. Let's call this a line-triplet. The pointer should pick out a dark stone which punctuates the line-triplet. This stone carries an inscription which you can't read but I have a photograph of it at www.cl.cam.ac.uk/~fhk1/Sundials/Misc/Stone.jpg You will see that the inscription says: These paving lines are one tenth of a second of longitude or 18.1 m apart 51°30'03"N 0°00'23"E This is intriguing because almost everything it says is untrue, or at best, misleading!! Zoom out a little and you will certainly see neighbouring line-triplets. To get to the neighbour on the right, key in: 51 30 4.75 00 00 16.85 We are at the same latitude but 0.94" further to the east. How does this square with "one tenth of a second of longitude"? Also, where on Earth does the 18.1m come from? At the latitude of Greenwich I make it that one arc-second of longitude is about 19.4m so one tenth of a second would be 1.94m. Are they lines of longitude? Of course that is only an implication but it is pretty strongly implied... If you slide one of these line-triplets to one of the vertical edges of your window you will see that it fails to align by about 1 degree. If they are lines of longitude they have been pretty poorly surveyed. Where does the 51 30 03 00 00 23 on the stone come from? Without knowing which coordinate system they are using it is hard to say. If you naively key this into the search box you will find you land on the roof of a building. OK, this may simply mean they are not using the same longitude reference as Google. Fortunately we have the roof of the Airy transit instrument nearby for calibration purposes and this obligingly DOES run true north-south!! Key in: 51 28 39.96 -00 00 5.3 Yes, a minus is allowed by the syntax too. The pointer indicates the rough centre of the roof above Airy's transit instrument. If you are the right kind of enthusiast, this is the "Prime Meridian of Longitude". The longitude quoted suggests we might try subtracting 5.3" from the 23" on the stone. Key in: 51 30 03 00 00 17.7 Bingo! We seem to have hit an inscription stone. Shame it is the wrong one! I suspect it has been moved! I haven't been able to find documentation about these lines from a simple search. Maybe another reader knows about them? All this hard-landscaping must have cost shed-loads of money. What a pity they didn't get it right. Happy surfing Frank Frank H. King Cambridge, U.K. --------------------------------------------------- https://lists.uni-koeln.de/mailman/listinfo/sundial ----- No virus found in this message. Checked by AVG - www.avg.com Version: 2014.0.4745 / Virus Database: 4007/8080 - Release Date: 08/22/14 ----- No virus found in this message. Checked by AVG - www.avg.com Version: 2014.0.4745 / Virus Database: 4007/8080 - Release Date: 08/22/14
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